The present invention relates to a process and device for mounting a sub-assembly, comprising at least one spray for spraying coating product, on a mobile part of a robot.
Automatic coating product spray installations must be capable of considerable flexibility in order to minimize the investments that they involve. Different types of coating product sprays exist at the present time, such as rotary sprays, pneumatic sprays and electro-pneumatic sprays. On the other hand, the nozzle, the possible bowl and the possible electrostatic charge system must be adapted, as a function of the type of coating product, which may be a base paint, a varnish, a metallic paint, a solvent-based or hydrosoluble paint.
In known installations, only one type of spray is generally provided to be used. For example, in the case of an installation for coating automobile vehicle bodies, it is known to equip a coating booth with one type of spray for substantially the whole life duration of the booth. It might be envisaged to use different booths, each comprising a type of spray devoted to a type of application, but this would involve considerable investments which could not be economically worthwhile.
It is a particular object of the present invention to overcome these drawbacks by proposing a process and a device which reliably and rapidly mount a sub-assembly on a robot and which, during operation, adapt the type of spray used to the type of application desired and/or to the type of product to be sprayed.
To that end, the invention relates to a process for mounting a sub-assembly, comprising at least one coating product spray, on a mobile part of a robot, characterized in that it consists in:
engaging a support fast with the mobile part in a ring connected to said sub-assembly;
rotating this ring with respect to this support by bringing first projections provided on the periphery of said ring opposite second projections provided on the periphery of said support, and
displacing a bearing plate, connected to this mobile part, in the direction of this sub-assembly, until this plate exerts a bearing effort on the sub-assembly, this bearing effort being transmitted to the ring, with the result that the first and second projections are brought into mutual engagement.
Thanks to the invention, the ring and the support together constitute a system of locking by rotation, similar to a bayonet system or to a so-called xe2x80x9cquarter-turnxe2x80x9d system, even if the relative angle of rotation of the ring with respect to the support is not necessarily 90xc2x0. The movement of the bearing plate makes it possible to rigidify the assembly produced by the ring and the support and also to ensure tightness of fluid and/or electrical connections made at the interface between the robot and the sub-assembly in question. The process of the invention induces solely a movement of rotation of the ring and a movement of longitudinal displacement of the bearing plate, which may be a translation, these movements being mechanically simple and adapted to be effected particularly rapidly, with the result that the mounting of the sub-assembly and dismantling thereof may be compatible with the production rates of the automobile industry.
According to an advantageous aspect of the invention, the displacement of the bearing plate is obtained by supplying air under pressure to a closed volume defined between the support and the bearing plate. This mode of control of displacement of the piston makes it possible to obtain a considerably rapid movement and intense bearing force of the bearing plate on the sub-assembly. In this way, the effort of mutual engagement of the projections depends on the supply pressure of this closed volume.
The invention also relates to a device for carrying out the process as defined hereinbefore and, more specifically, to a device which comprises:
a ring connected to the sub-assembly and provided, on its periphery, with first projections;
a support fast with the mobile part and provided, on its periphery, with second projections;
a bearing plate borne by the mobile part and adapted to be displaced with respect to the support in a direction substantially parallel to a central axis of this support;
the first and second projections being adapted to be brought into mutual engagement when the ring surrounds the support, the bearing plate being adapted to exert on the sub-assembly an effort of locking of these projections.
According to advantageous aspects of the invention, the first and second projections comprise studs made on an inner radial surface of the ring and on an outer radial surface of the support and adapted to be aligned when the ring is disposed around the support. In that case, the surfaces of the studs intended to come into mutual abutment are advantageously provided with respective centering means, these centering means being able to comprise a housing, provided on one of the surfaces of one of the studs for receiving a projecting element made on the corresponding surface of another stud.
The bearing plate comprises orifices for the passage of fluid supplying the spray, these orifices being adapted to be aligned with corresponding orifices in the sub-assembly, and/or an electrical connector adapted to cooperate with an electrical connector provided on the sub-assembly for supplying the spray with current. Thanks to the mobile nature of the bearing plate, a satisfactory seal is obtained between the orifices of the bearing plate and those of the sub-assembly, while the electrical connection made thanks to the connectors is reliable and protected from its environment.
The bearing plate is provided with an orifice for the passage of a control rod of a piston of a reservoir incorporated in the sub-assembly for supplying coating product to the spray or sprays.
A closed volume is defined between the support and the bearing plate, this closed volume being adapted to be selectively connected to a source of pressurized air, the value of the pressure in this volume enabling the displacement of the bearing plate to be controlled.
The ring is provided with projections adapted to cooperate with projections with corresponding shapes provided on a manoeuvring ring belonging to a station for cleaning/filling the sub-assembly for controlling the displacement of this ring in rotation.